Abstract: The effect of controlled rolling (CR) process on the microstructure and mechanical properties of Q390 HSLA heavy plate was investigated by way of lab simulation test with process parameters optimized. The results showed that the 50 mm-thick heavy structural plates rolled with these parameters have high strength with better low-temperature toughness, i.e., Rm > 517 MPa, ReL> 382 MPa and the ductile-brittle transition temperature is in the range from -60°C to -70°C. Such properties are up to the standard GB/T1591-94. Holding the temperature below the complete solution temperature of Nb (C, N) makes for the improvement of the low-temperature toughness of steel. The number of rolling passes and finish rolling temperature from 830°C to 780°C have no remarkable effect on microstructure and properties of the plates when the total reduction of finishing pass and air cooling schedule remain unchanged.